The present invention relates to a pipe assembly, and more particularly, to a pipe assembly which uses a locking ring to join two pipe sections.
Pressurized pipe lines such as water lines are subjected, as a result of internal pressure and change of direction or size of pipe, to thrust forces which tend to separate the pipe sections from each other. This tendency of the pipe sections to separate is typically resisted through the use of thrust blocks or, alternatively, a harnessed joint may be used.
Harness joints are generally formed with a bell ring located on one pipe section and a spigot ring located on a second pipe section which fits and seals within the bell ring. In addition, some means of holding the bell and spigot rings together are provided.
A typical means of holding the bell and spigot rings together is a split locking ring positioned between the inner face of the bell ring and the outer face of the spigot. A known locking ring arrangement is shown in U.S. Pat. No. 3,776,576 to Keyser and assigned to the assignee of the present application. This patent discloses a locking ring having a pair of lugs which extend through a slot in the bell ring and which are drawn together by a fastener to firmly attach to the spigot ring after the spigot ring is in place within the bell ring. In order to hold the locking ring in an expanded position within the bell ring prior to the spigot ring being received into the bell ring, a spacer block is provided between the lugs on the locking ring to hold the lugs apart by a predetermined amount. Prior to tightening the ring, the fastener passing through the lugs and the spacer block must be removed such that the spacer block may be extracted after which the fastener is replaced to tighten the lugs together and thus contract the locking ring around the spigot ring.
As a result of differences in tolerances in the length of the blocks and the circumferences of the bell and spigot rings as well as in the length of the locking ring, the locking ring is not always expanded to a large enough circumference to permit the locking ring to be fully recessed within the bell ring such that a gasket positioned on the end of a spigot ring entering the bell may catch on exposed edges of the locking ring.
In addition, the block is difficult to work with in field conditions since the fastener must be removed in order to extract the block from between the lugs prior to tightening of the locking ring. Thus, there is a potential for losing the fastener during the fastener removal and installation operation. This is particularly a problem when the ring is located in a limited access area or when the operation must be performed under water.
The spacer block has also proven difficult to work with in situations where the pipe sections must be separated for some reason prior to completing the joint but after the spacer block has been removed. In this type of situation, a special tool must be provided for prying the lugs of the locking ring apart in order to reinsert the block for holding the ring in an expanded position.
Thus, there is a need for a harnessed pipe assembly using a locking ring in which means are provided for maintaining the ring in an expanded position and which do not require removal prior to contracting the ring. Further, there is a need for providing means for conveniently moving the locking ring from a contracted to an expanded position within a bell ring such that a gasket positioned on the end of a spigot ring entering the bell ring may pass into the bell ring without catching on the locking ring.